Ultimathnum 0.6.0

What hasn't changed? Wait, there's a new module too!?

• Various API and non-API changes (0.y.z).
• #41 Make DoubleInt great again!
• #40 New BitCountable protocol
• #38 Miscellaneous 0.6.0 stuff
• #37 Order and Signedness enums (no protocols)
• #36 Flush shifts greater than IX.max
• #35 No masking shift requirements
• #34 Mark all infinite-by-finite divisions as errors
• #32 Generic shift operations
• #31 Pointer-bit binary integer bit counts
• #30 Rework lsb/msb stuff
• #29 Optional DataInt.Body elements
• #27 DataInt.Body/isEmpty
• #23 StdlibIntKit